Lemuel Augustus Penn (September 19, 1915 – July 11, 1964) was the Assistant Superintendent of Washington, D.C. public schools, a decorated World War II veteran, and a Lieutenant Colonel in the United States Army Reserve. He had earned a Bronze Star for service in New Guinea and the Philippines and had contributed to Gunnar Myrdal's landmark study of race relations, An American Dilemma. At the time of his death he was the father of three children.
On July 11, 1964, Penn was driving home to Washington, D.C. from Fort Benning, Georgia, with two other Black Reserve officers, following their annual summer training camp. Authorities later alleged that three white members of the United Klans of America — James Lackey, Cecil Myers, and Joseph Howard Sims — saw the officers' Chevrolet Biscayne in Athens, Georgia, and followed it. Prosecutors alleged that, as the two cars reached a bridge over the Broad River on Georgia State Route 172 in Madison County, near Colbert, Myers and Sims fired shotguns into Penn's vehicle, killing him.
Authorities identified Myers, Sims, and Lackey as suspects. Sims and Myers were tried for murder in Georgia state superior court but were acquitted by an all-white jury in September 1964. Federal prosecutors subsequently charged them under 18 U.S.C. § 241 with conspiring to interfere with Penn's civil rights. In June 1966, a federal conspiracy trial began against Sims, Myers, Lackey, and three additional defendants — Herbert Guest, Denver Phillips, and George Hampton Turner. A federal jury convicted Sims and Myers of conspiracy; the four co-defendants were acquitted. Sims and Myers each received the statutory maximum sentence of 10 years and served approximately six years.
A historical marker was later erected at the Georgia Highway 172 Broad River Bridge site by the Georgia Historical Society, the Lemuel Penn Memorial Committee, and Colbert Grove Baptist Church, commemorating Penn and describing the case's role in prompting expanded federal civil-rights prosecutions. The federal indictment arising from Penn's killing led to United States v. Guest, in which the U.S. Supreme Court reinstated the conspiracy charge and addressed federal power to prosecute private conspiracies involving state participation.